This invention relates to electronic display and, more specifically, to a circuit for driving an external electrode gas discharge display panel, commonly referred to as a plasma display panel.
A per se well known external electrode gas discharge display panel comprises first and second sets of electrodes. Each first electrode is disposed spatially opposite some or all the second electrodes with a gas discharge cell interposed therebetween, together with an insulating layer between the gas discharge cell and either one or both of the facing first and second electrodes. Circuits for driving an external electrode gas discharge display panel may be broadly classified into two types. A display driver circuit of a first type comprises a pair of drivers, one for selectively supplying first pulse sequences to the first electrodes, the other for selectively supplying second pulse sequences of an opposite phase to the second electrodes. The pulse voltage is from 130 to 160 volts. A gas discharge occurs in the cell disposed at each intersection of the first and second electrodes to which the pulses are supplied.
A display energizing circuit of a second general type comprises a driver and a switching circuit. The driver selectively supplies pulse sequences to selected of the first and second electrodes. The switching circuit selectively renders the others of the first and second electrodes on and off, e.g., grounded or ungrounded. The pulse voltage is from 260 to 320 volts. A gas discharge occurs in the cell situated at each intersection of the electrodes supplied with the pulses and the electrodes rendered on.
In a circuit of the first type, transistors capable of withstanding a high voltage must be used for each electrode. When the number of electrodes is large, the circuit is complex and expensive. Moreover, due to the high pulse voltage, it is very difficult to realize the circuit with an integrated circuit construction. As for the driver of a circuit of the second type, a transistor which can withstand a high voltage must again be employed for each electrode. The high voltage withstanding capability, however, is unnecessary for the transistors of the switching circuit. It is thus readily possible to fabricate the switching circuit in integrated circuit form. It has been mandatory, however, to use a d.c. source of a high voltage. Furthermore, the power consumption during switching has been considerable.
In U.S. Pat. No. 3,953,762 issued to Tsunekiyo Iwakawa and Akira Yano, assignors to the instant assignee, a circuit of the second type is disclosed wherein the circuitry is simplified. It is still necessary, however, to use a clock pulse generator and a second or auxiliary d.c. source. The power consumption is still considerable because a main power supply of a high d.c. voltage is required.